1 . Field of the Invention
The present invention relates to a semiconductor device, more particularly, a semiconductor device allowing for improved breakdown voltage.
2 . Description of the Background Art
In recent years, in order to achieve high breakdown voltage, low loss, and the like in a semiconductor device, silicon carbide has begun to be adopted as a material for the semiconductor device. Silicon carbide is a wide band gap semiconductor having a band gap larger than that of silicon, which has been conventionally widely used as a material for semiconductor devices. Hence, by adopting silicon carbide as a material for a semiconductor device, the semiconductor device can have a high breakdown voltage, reduced on-resistance, and the like.
An exemplary semiconductor device employing silicon carbide as its material is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like. The MOSFET is a semiconductor device that controls existence/non-existence of an inversion layer in a channel region in accordance with a predetermined threshold voltage so as to conduct and interrupt a current. For example, Japanese Patent Laying-Open No. 2005-328013 describes a trench gate type MOSFET in which a channel region is formed along a trench wall surface.